黔西南“大厂层”地质特征及其对金矿的控制作用研究

发布时间：2018-05-07 20:20

本文选题：卡林型金矿 + “大厂层”　；参考：《成都理工大学》2015年硕士论文

【摘要】：卡林型金矿石金矿是世界金矿最重要的来源,也是我国第二大金矿类型。黔西南是我国卡林型金矿集中产出的地区之一,是“滇黔桂”卡林型金矿矿集区的主体部分,区内分布了大量的超大型、大型、大中型金矿床,。国内外不少学者针对该区域进行了大量的研究工作,取得了许多重要的研究成果。本文主要针对于黔西南卡林型金矿密切相关的控矿构造:“大厂层”以及高角度断层地质特征及与金矿的关系展开研究,并选取了水银洞金矿以及烂泥沟金矿两个典型的矿床进行了包括含矿层位、流体特征、稳定同位素特征等方面的对比研究。系统描述了不同矿床“大厂层”的区域分布、野外特征以及总结了与金矿的关系,同时对比了盆地相区与台地相区矿床在控矿构造以及成矿过程的共性以及个性。通过以上研究,主要的认识如下:(1)由于早期构造作用,区域上形成了具有明显的台-盆交错的构造轮廓,其定型于印支-燕山期,较早形成的东西向构造往往被后期形成的北东向和南北向构造叠加改造。在台地相区与盆地相区之间存在一个明显的相变线,由该相变线控制了台地相区碳酸盐岩与盆地相区碎屑岩的分布,两者之间呈现一个突变的关系。实际上,该相变线是一个大型的逆冲推覆构造,台地与盆地之间有明显的断裂现象,呈现断层接触的现象。(2)“大厂层”主要为一套产于茅口组(P2m)与龙潭组(P3l)或峨眉山玄武岩组(P3β)这一沉积间断-不整合界面中的深灰色-黄灰色中厚层强硅化角砾岩或角砾状粘土岩及角砾状凝灰岩组合,以角砾状构造以及强硅化蚀变为最主要的识别特征。在有些矿床中,“大厂层”未出露于地表,例如水银洞金矿,而有些矿床中却出露于地表,例如泥堡金矿、戈塘金矿。(3)区域上这一大界面同时形成,在经受不同后期次级构造作用下造成了“大厂层”与高角度断层产状的不同。两类构造均对金矿有着明显的控制作用。通过对于台地相区与盆地相区典型的赋金层序的对比,作者认为黔西南的主要赋金层位均遵循一个规律:形成在脆性岩石和塑性岩石的接触界面上。主要原因是在这样一个岩石能干性不同的界面上易于发生层间滑动,另外上下岩性的孔隙度的突变,使得流体压力增大,造成围岩破碎,导致成矿物质的沉淀。所以本文认为,“大厂层”的概念应该扩大为:包括台地相区传统“大厂层”以及盆地相区高角度断层在内的一系列岩层能干性变化的界面。(4)流体包裹体的研究表明,两类控矿构造中成矿流体均为低温、低盐度的热液。“大厂层”中含有少量CO2、CO以及CH4等气体,高角度断层中几乎不含气体成分。流体成分测试结果显示,“大厂层”流体中阳离子均以Na+、K+和Ca2+为主,其次为Mg2+,阴离子方面,两类层位中均以F-、Cl-、SO42为主,高角度断层中的阴离子相比“大厂层”中有明显的增加。稳定同位素示踪研究显示,“大厂层”的流体来源是深部与大气降水的共同作用,烂泥沟矿床的流体来源主要是变质水热液与深部流体来源,同时也有大气降水的参与。(5)黔西南金矿的形成是“大厂层”与区域逆冲推覆构造共同作用的结果。成矿早期的流体来源于深部的岩浆水,通过区域大型的逆冲推覆构造所形成的深大断裂向上运移至容矿构造时,大气降水的加入,使流体发生了混合作用,促使有利于矿物沉淀化学反应的发生。当运移至容矿构造时,由于压力的突然降低,流体发生沸腾作用,造成H2O以及CO2等气体的丢失,成矿物质浓度增加,进而析出沉淀。流体与围岩所发生的化学反应同样也促进了成矿物质的活化析出,最终成矿。成矿物质在“大厂层”中主要是以Au-S与Au-Si络合物形式迁移,高角度断层中Au主要是以Au-S络合物和Au-Cl络合物形式迁移。
[Abstract]:Carlin type gold ore gold deposit is the most important source of gold mine in the world, and it is also the second largest type of gold mine in China. In Southwest Guizhou, one of the areas of concentrated output of Carlin type gold deposits in China is the main part of the "Yunnan Guizhou Guangxi" Carlin type gold ore collection area, and a large number of large, large, medium and large scale gold deposits are distributed in the region. Many scholars at home and abroad have been aiming at the area. A lot of research work has been carried out in this area, and many important research results have been obtained. This paper mainly focuses on the closely related ore control structure of Carlin type gold deposits in southwestern Guizhou: "great plant layer" and the geological characteristics of high angle faults and the relationship with gold deposits, and selected two typical ore deposits of the water silver cave gold ore and the unfinished gold mine. The bed has carried out a comparative study of the ore bearing strata, fluid characteristics and stable isotopic characteristics. The systematic description of the regional distribution of the different ore deposits, the characteristics of the field and the relationship with the gold deposits, and the comparison of the commonness and individuality of the ore deposits in the basin and the mesa facies areas in the ore control structure and the metallogenic process are compared. Through the above research, the main understanding is as follows: (1) because of the early tectonic action, the region formed a clear platform basin interlaced tectonic outline, which was formed in the Indosinian Yanshan period, and the East-West structure, formed earlier, was often overlaid by the late north-east and North-South structures, and there was one between the platform and the basin facies. An obvious phase transition line, which controls the distribution of clastic rocks in the carbonate rock and basin facies area of the mesa phase area, shows a catastrophic relationship between the two. In fact, the phase transition line is a large thrust nappe structure, there are obvious fracture phenomena between the platform and the basin and the phenomenon of fault contact. (2) "big factory layer" principal. A set of deep gray and yellow gray medium thick silicified breccia or breccia like clayite and breccia tuff in the discontinuous and unconformable interface of the P2m and the Longtan Formation (P3l) or the Mount Emei basalt group (P3 beta) is the most important identification characteristic of the breccia structure and strong silicified alteration. "Dachang layer" is not exposed to the surface of the earth's surface, such as the silver cave gold deposit, but some deposits are exposed to the surface, such as the mudbao gold ore, the Ge Tong gold mine. (3) this large interface is formed at the same time, which has resulted in the difference between the "big plant layer" and the high angle fault. The two types of structures are all clear to the gold deposits. By comparing the typical gold bearing sequences in the mesa and basin facies areas, the authors believe that the main gold bearing beds in southwestern Guizhou follow one rule, which are formed on the contact interface between brittle rocks and plastic rocks. The main reason is that interlayer sliding is easy to occur on such a rock with different energy and dry interfaces. The mutation of the porosity of the upper and lower lithology makes the fluid pressure increase and cause the breakage of the surrounding rock and lead to the precipitation of the minerals. Therefore, this paper holds that the concept of "great plant layer" should be expanded to include the traditional "large plant layer" in the platform facies area and the interface of a series of dry changes in a series of strata within the high angle fault in the basin facies area. (4) fluid The study of inclusions shows that the ore-forming fluids in the two types of ore control structures are low temperature and low salinity. The "big factory layer" contains a small amount of CO2, CO and CH4 gases, and there are almost no gas in the high angle faults. The results of the fluid composition test show that the cations in the "big plant" fluid are mainly Na+, K+ and Ca2+, followed by Mg2+, and negative. On the other hand, F-, Cl- and SO42 are the main types of the two stratigraphic beds, and the anions in the high angle fault are obviously increased compared to the "big factory layer". (5) the formation of gold deposits in southwestern Guizhou is the result of the joint action of the "great plant layer" and the regional thrust nappe structure. The fluid of the early mineralization was derived from the deep magmatic water, and the atmospheric precipitation was added to the deep faults formed by the large area large thrust nappe structure to the ore bearing structure. It makes the fluid mixing and promotes the occurrence of chemical reaction in the mineral precipitation. When the movement is moved to the ore bearing structure, the fluid is boiling, resulting in the loss of H2O and CO2, and the concentration of the ore-forming material increases and then precipitates. The chemical reaction of the fluid and the surrounding rock also promotes the chemical reaction. The mineralization material is activated and precipitated. The metallogenic material is mainly migrated in the form of Au-S and Au-Si complex in the "great plant layer", and the Au in the high angle fault is mainly migrated in the form of Au-S complex and Au-Cl complex.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51

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